1. Field of the Invention
The present invention is related to a power control device, and more particularly to a power control device capable of detecting the condition of the sensing resistor.
2. Description of the Prior Art
As the functions of electronic products become more and more complicated, the electronic products adopt more and more electronic elements to meet the requirement. Since different electronic elements may have different power specification, such as different working voltages and different working currents, power systems are required to provide power supplies for different electronic elements after the electronic product receive the input power. For example, if the electronic elements require five different working voltages, such as 1.2 V, 3.3 V, 5 V, 7 V, and 12 V, then the power system may use five different power control devices to convert input power into appropriate working voltages for different electronic elements.
Generally, as long as the electronic product keeps operating, the power control device would have to output power to the electronic product consistently. Since the stability of the power supply is crucial in terms of performance of the electronic product, the reliability of the power control device has become one of the important quality factors. In addition, when the power control device operates for a long time with high currents, it would dissipate heat to damage electronic components. To prevent this, the prior art uses a sensing resistor to sense the current generated by the power control device, and turn off the output switch of the power control device when the current is overrated, preventing the electronic components from being damaged. That is, the over-current protection (OCP).
However, in prior art, if the sensing resistor is short-circuited, the power control device would not be able to detect the current, and fail to perform the OCP function. Therefore, the output switch will remain turned on, damaging to the electronic components.